File sharing refers to the provision for sharing (receiving or distributing) digital files and/or content via a network. In many cases the file sharing involves a peer to peer connection, where content is at least partially received from one or more other end users of the content, which already possess a copy of the desired content. Such a distribution model differs from other instances in which a central server maintains and distributes the content. The peer to peer model benefits from the advantages of a more distributed distribution approach, where a larger number of sources of the content, each having an independent ability to source the content including processing power and distribution band width, are used to supply one or more portions of the content. A particular content recipient can receive different portions of the content from separate sources, which helps to minimize and/or spread the load or impact on any particular source of the content.
Furthermore the presence of multiple sources serves to provide a degree of redundancy, which can be used to accommodate the dynamic nature of networks, such as the Internet, where any particular source's presence on the network may be temporary and/or transient. If a particular source ceases to be available during the download of content, another suitable source is identified and accessed to supply the remaining portions of the content that has yet to be received.
Such a distribution model for content has become very popular for use on personal computers. As such, much of the available content via this distribution model is formatted for use in that environment. Increasingly, users are wanting to access the same or similar content using more portable devices, such as personal digital assistants or cellular telephones. However, much of the available content is formatted for being viewed on the relatively higher fidelity interfaces more commonly associated with personal computers. Additionally, the more limited storage associated with the more mobile devices has diminished the availability of content formatted at a quality level that is suitable for rendering by the more mobile devices.
In some instances the ability to more readily scale content has benefited from the increasing availability of scalable codecs for audio, image or video files, which can sometimes be more readily used to change the quality of the file by adapting the dimensions, the frame rate, and/or other quality factors of the content, without first needing to decompress the information, and subsequently recompress the information after the appropriate quality conversion. At least a couple of scalable techniques include bitplane coding and enhancement layer encoding, which assists in making available a desired portion associated with a particular quality level.
In bitplane coding, scalable coding of the media blocks is generally achieved by coding a block of audio/video transform coefficients bitplane by bitplane, from the most significant bitplane to the least significant bitplane.
In enhancement layer encoding, the media content is compressed into a base layer and one or more enhancement layers, each of which typically occupies a separate channel. A minimum quality media stream is coded in the base layer. With the addition of each successive enhancement layer in addition to the base layer, the quality of the decoded media improves.
However even with the availability of scalable codecs, many peer to peer applications have difficulty managing multiple source files of the same content having differing versions of quality, as the more traditional peer to peer models, are unable to establish a useable relationship between the different versions of the same content. In absence of being able to recognize a useable relationship between the different versions, the different versions are treated by many peer to peer distribution systems as being separate independent and distinct forms of content.
Consequently, the present inventors have recognized that it would be beneficial if the content that is readily available in differing quality levels from multiple peer sources might be identified and adapted to be received and combined at a suitable quality level for use on a more mobile device having greater limitations on data throughput as well as the reproducible quality levels for content that is intended to be rendered by the device.